The present invention relates generally to plugs used for treatment of the human eye, and more particularly to removable plugs used to temporarily close the punctal openings of the eye for treatment of the symptoms of dry eyes, and other symptoms related to tear drainage into the nasal lacrimal duct.
In the past, various different plugs, implants or other devices have been used to treat keratoconjunctivitis sicca, or dry eyes, and to decrease or stop tear drainage into the nasal lacrimal duct, which may cause such diverse symptoms as post nasal drip, sinusitis, allergies, headaches, snoring, etc. For example, U.S. Pat. Nos. 5,171,270, issued to Herrick on Dec. 15, 1992, and No. 5,163,959, issued to Herrick on Nov. 17, 1992, disclose an implant adopted to be inserted into the lacrimal duct of an eye. The implant has an elongated member having a medial tapered end and a collapsible flared flange attached to the opposite lateral end of the elongated member. The tapered end facilitates inserting the implant into the duct. The implant is placed into the lacrimal duct by inserting a tool into the collapsible flared flange and forcing the implant into the duct. As the implant is inserted, the collapsible flared flange collapses, and the flange engages the interior walls of the canaliculus.
Another implant is disclosed in U.S. Pat. Nos. 5,049,142, issued to Herrick et al. on Sep. 17, 1991, and No. 4,660,546, issued to Herrick et al. on Apr. 28, 1987. These patents describe a piece of catgut which may be inserted into the canaliculus. The catgut will swell in the canaliculus, and remain in place before it dissolves. A cylindrical implant may be used, which has a conically-shaped front portion to facilitate insertion into the canaliculus. The implant may have passageways therein to permit varying amounts of tears to pass through it. The implant may also be made from nonabsorbable materials, such as rubber or plastic.
U.S. Pat. No. 4,959,048, issued to Seder et al. on Sep. 25, 1990, discloses a lacrimal duct occluder having a shaft, a rounded cap attached to one end of the shaft, one or more conical segments attached to the other end of the shaft, and a rounded tip. The occluder is formed from a flexible, inert, non-toxic, medical grade silicone elastomer, and may be bent to conform to the shape of the lacrimal duct.
A punctum plug for controlling flow of lacrimal fluid through the tear ducts of an eye is described in U.S. Pat. No. 4,915,684 issued to MacKeen et al. on Apr. 10, 1990. The plug has a generally cylindrical body portion, a rounded head portion at one end thereof, and one or two peripheral members at the other end. The peripheral members are frustrum-shaped to facilitate inserting the plug into a duct, and retaining the plug in the duct.
Another punctum plug is disclosed in U.S. Pat. No. 3,949,750, issued to Freeman on Apr. 13, 1976. The punctum plug has a projecting tip or barb portion which dilates and blockingly protrudes into the canaliculus, a middle body or waist portion of smaller diameter around which the punctal sphincter ring tightens, and a larger smooth head portion. The plug is inserted by first dilating the punctal opening and canaliculus using a dilator tool, and then inserting the plug using a forceps or inserter tool.
A replacement tube for the lacrimal ducts is disclosed in U.S. Pat. No. 3,726,284, issued to Parker on Apr. 10, 1973. The tube is fabricated from glass or stiff plastic. It has elongated end portions and an expanded portion near the middle of the tube, which joins the elongated portions. The elongated portions and expanded portion have drain passages passing therethrough. A combined punctum plug dilator and insertion tool is shown in U.S. Pat. No. Des. 295,445, issued to Freeman on Apr. 26, 1988.
Other plugs or devices used for purposes other than treatment of the human eye are disclosed in U.S. Pat. Nos. 5,131,906, issued to Chen on July 21, 1992 (incontinence device); 4,281,658, issued to Child on Aug. 4, 1981 (dilator for teat of mammal); No. 3,858,571, issued to Rudolph on Jan. 7, 1975 (cornual plug used to obstruct entry to Fallopian tubes); No. 3,721,229, issued to Panzer on Mar. 20, 1973 (obturator device for injection of radiopaque substances into body cavity); No. 3,703,898, issued to Zackheim on Nov. 28, 1972 (teat dilator); and No. 3,463,141, issued to Mozolf on Aug. 26, 1969 (male contraceptive device).